Kay9,
It depends on how you have set up the Message Notification and the Mailbox.
If you leave the flag, Deliver Hangup Message when ANI is available the mailbox will create a new message when no message is left IF there is Caller ID information.
If you set Remote Messaging to Yes in that mailbox you can go into Primary Notification and set Call for Each New Message to Yes.
When you drill further down you set up how and where to call for those messages and the timers. It seems you know how to do that part so I will not go into further detail on that.
Thanks,
TE